1. Field of the Invention
The present invention relates to printing technology using ink jet recording apparatuses that print characters and images on a recording medium by jetting ink droplets out of nozzle openings so as to correspond to print data.
2. Discussion of the Related Art
Some ink jet recording apparatuses that carry a recording head using piezoelectric vibrators as actuators can control the size of an ink droplet by controlling the size and timing of a drive signal to be supplied to an actuator. Therefore, high resolution printing can be implemented, and hence these ink jet recording apparatuses are particularly suitable for applications requiring high printing quality.
In processing graphic data, such printing apparatuses have to handle a large volume of data sent from a host, and therefore have their print speed limited by the print data transfer speed and the data processing speed. On the other hand, in processing text data, such printing apparatuses receive a smaller volume of data per unit time, and therefore have their maximum print speed determined by the recording head drive frequency.
Therefore, for increasing the text data print speed, one possible technique is to increase the recording head drive frequency. However, from such a technique arises the problem of elevated cost since the recording head must be reformed.
To overcome this problem, ink jet recording apparatuses may reduce the number of printed dots by thinning pixel data to be printed. However, this brings about the problem of extremely impaired printing quality.
Text data printing quality improves with increasing dot density. However, when the dot density exceeds a certain level, usually 360 dpi or more, the improvement in printing quality practically tops out, providing no remarkable improvement in appearance.
SUMMARY OF THE INVENTION The present invention has been made in view of the aforementioned circumstances. An object of the present invention is therefore to provide a high speed print method for an ink jet recording apparatus that can implement text data printing at a speed higher than the normal printing performance of the recording head without reforming the recording head or bringing about significant impairment of printing quality.
A second object of the present invention is to provide an ink jet recording apparatus suitable for implementing the aforementioned high speed print method.
To overcome the aforementioned problems associated with the prior art, the present invention is directed to a high speed print method for an ink jet recording apparatus that involves the steps of: developing a single pixel in a print signal into a plurality of pieces of bit map data; thinning a plurality of pieces of bit map data allocated for a single pixel in such a manner that at least a single dot is included; and jetting an ink droplet by increasing a moving speed of a recording head so as to correspond to the thinning operation.
Since dot data that includes at least a single bit per pixel is printed, there is no significant impairment of printing quality, and print speed can be increased in proportion to the number of dots reduced.